1. Field of the Invention
This invention relates to a slide actuator, and more specifically to a slide actuator wherein roller bearings are disposed within channels defined between a cylinder body and a slide table so as to enhance the load-resistance characteristic of the moving slide table.
2. Description of the Related Art
When a work item is displaced with high accuracy under the action of a conventional fluid pressure cylinder, there is used a structure wherein guide rods are respectively mounted to piston rods and the plate to be driven is held in engagement with the leading ends of both the piston rods and the guide rods. When the plate is displaced under the actuation of the cylinder, the plate is guided by the guide rods, and the guide rods advantageously share or support a portion of a load, thus enabling the conveyance of the work item or the like with relatively satisfactory accuracy.
In such a cylinder, the guide rods are in the form of a column or a cylinder. The accuracy of guiding the plate by the guide rods is obtained by supporting the guide rods with ball bushings within a cylinder body. Thus, circumferential side surfaces of the guide rods are held in point-to-point contact with spherical surfaces of the ball bushings. When the load acts on the guide rods from the plate in this condition, the load, i.e., the pressure applied to both the circumferential side surfaces of the guide rods and the spherical surfaces of the ball bushings, is maintained at an allowable pressure or lower. Therefore, the pressure applied to the guide rods can be reduced by increasing the curvature of each guide rod and the areas at which the guide rods make contact with ball bearings fitted on the ball bushings. However, the cross-section of each guide rod (and hence its size and weight) will increase as the curvature is increased. Thus, the prior art cannot reduce the actuator in size and weight.